Samsung SCH-211 Service Manual page 23

Circuit Description
5-1-3 Baseband Part
MOBILE SYSTEM MODEM (MSM)
The MSM equipped with the INTEL 80186 CPU
core is an important component of the CDMA
cellular phone. The MSM comes in a 176 pins
TQFP package. The interface block diagram is
shown on page 6-3.
MICROPROCESSOR INTERFACE
The interface circuitry consists of reset circuit,
address bus (A0-A19), data bus (AD0-AD15), and
memory controls (ALE, DT_R, HWR/, LWR/,
RAM_CS/, ROM_CS).
INPUT CLOCK
¦UCPU clock: 27 MHz
¦UTXCO/4 (pin 34): 4.92 MHz. This clock signal
from the BBA is the reference clock for the MSM
except in CDMA mode.
¦UCHIPX8 : 9.8304 MHz. The reference clock
used during the CDMA mode.
BBA INTERFACE
CDMA, FM Data Interface
¥ TXIQDATA0-7 (pins 24-32) : TX data bus used
during both CDMA and FM mode.
¥ C_RX_IDATA0-3 (pins 16-20) and
C_RX_QDATA0-3 (pins 12-15) : RX data bus
used during CDMA mode.
¥ FM_RX_IDATA (pin 7) and FM_RX_QDATA
(pin 8) : RX data bus used during FM mode.
Clock
¥ TX_CLK (pin 22), TX_CLK/(pin 23) : Analog to
Digital Converter (ADC) reference clock used in
TX mode.
¥ CHIPX8 : ADC reference clock used in CDMA
RX mode.
¥ FMCLK : Reference clock in FM RX mode.
5-2
ADC Interface
ADC_CLK (pin 3), ADC_ENABLE (pin 1) and
ADC_DATA (pin 2) are required to control the
internal ADC in the BBA.
Data Port Interface
Includes the UART. Also, supports Diagnostic
Monitor (DM) and HP equipment interface.
CODEC Interface
The MSM outputs 2.048 MHz PCM_CLK (pin 19)
and 8 KHz CODEC_SYNC (pins 16,20) to the
CODEC (U117). The voice PCM data from the
MSM (U101) PCM_DIN (pin135) is compressed
into 8KHz by QCELP algorithm in the CDMA
mode. In FM mode, the data is processed by
D_FM.
RF Interface
TX : TX_AGC_ADJ (pin 35) port is used to control
the TX power level and PA_ON (pin 44) signal is
used to control the power amplifier.
RX : AGC_REF (pin 36) port is used to control the
RX gain and TRK_LO_ADJ (pin 45) is used to
compensate the TCXO clock.
General Purpose I/O Register Pins
Input/output ports to control external devices.
Power Down Control
When the IDLE/ signal turns LOW, only the TX
sections will be disabled. If both the IDLE/ and
SLEEP/ changes to LOW, all the pins except for
the TXCO is disabled.
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